Accidental fires are an ever-present phenomenon, and the provision of fire fighting equipment and the training of civilians as well as firefighters to handle fire fighting equipment effectively is an important and ongoing task.
A statistically significant number of accidents, ranging from minor burns or blisters to life threatening injuries, are associated with fire fighting training. Approximately 6000 injuries resulting from accidents which occurred during fire fighting training are reported each year. Additionally, approximately 6 deaths are reported each year as a result of accidents which occurred during fire fighting training exercises. These accidents are unnecessary and preventable; and, attributable in large part to fire fighting training methods and training equipment.
Over the past several decades, controlled "real fires", set in special buildings or open pits constructed of concrete, metal, or a combination of both, have been used to teach individuals basic fire fighting skills. Simulating "real fires" became a popular training method because the controlled fires create a realistic fire scenario without creating undue risk to the trainees.
The controlled "real fire" training methods and facilities have a number of drawbacks. For example, the facilities are expensive to construct and maintain. They are fixed in location, such that participants must travel to the facilities to obtain training. And, such "real" fires create conditions of considerable danger, are difficult to control, and generate unduly high temperatures. The temperatures of these controlled "real" fires can reach approximately 1200 to 1400 degrees F., which is greatly in excess of 550 degrees F., the maximum temperature tolerated by fire resistant safety suits. Finally, the fuels and methods used to ignite the fires generate large quantities of atmospheric pollution, as well as ground pollution.
The fire fighting training industry has made efforts to overcome the drawbacks associated with traditional training techniques. Examples of various fire fighting training devices are provided in the following United States patents: U.S. Pat. No. 5,055,050 to Rogers, et al., issued Oct. 8, 1991; U.S. Pat. No. 5,052,933 to Rogers et al., issued Oct. 1, 1991; U.S. Pat. No. 4,983,124 to Ernst et al., issued Jan. 8, 1991; U.S. Pat. No. 4,861,270 to Ernst et al., issued Aug. 29, 1989; U.S. Pat. No. 4,303,396 to Swiatosz, issued Dec. 1, 1981; and, U.S. Pat. No. 3,675,342 to Wolff, issued Jul. 11, 1972.
Of particular interest to the present invention is U.S. Pat. No. 5,055,050 to Rogers et al. which describes a fire fighting training device which uses an over-water combustion system. Gaseous combustion over water is also described in U.S. Pat. No. 3,038,054, which is directed to a decorative garden torch. U.S. Pat. No. 5,055,050 discloses a fire fighting trainer for use in training fire fighters to extinguish jet crash fuel fires and the like. The training apparatus comprises a fuel supply pipe and control valve, a perforated fuel distribution pipe, and an open top tank containing water within which the distribution pipe is disposed. When the supply pipe is opened, liquid fuel, preferably propane, passes through the perforations of the distribution pipe and is released into the water. The fuel passes as a vapor to the surface of the water and, due to its density, collects on the water's surface. U.S. Pat. No. 5,055,050 discloses that a gas pilot flame device may be used to ignite the vapor to form flames on the surface of the water, but does not disclose the structure of a suitable ignition system.
The simple ignition system described in U.S. Pat. No. 5,055,050 is suitable only to initiate ignition. The practical realities of a fire fighting training exercise make use of the ignition system during the course of the exercise impractcal and potentially dangerous. For example, during a training exercise, large quantities of liquid propane fuel are projected through the water bath. As the liquid propane passes through the water, the majority of it flashes to gas and is ignited. When it flashes to gas and is ignited, the propane expands in volume approximately 900 times. The liquid propane which does not flash to gas and ignite collects at the surface of the water and creates dangerous flammable pockets. It is important that the ignition pilot system is capable of maintaining a pilot flame so that the fuel burns off the surface of the water and does not accumulate. This potential hazard is not addressed by U.S. Pat. No. 5,055,050.
Additionally, the volume of water within the training tank rapidly increases during the training exercise as various fire fighting agents, such as foams, dry chemicals and water, are applied to the fire in an attempt to extinguish it. As a consequence, some of the gas is temporarily absorbed in the bath and overflows with the liquid contents of the bath.
The experience of the present inventors over the last decade in developing over-water combustion systems for use in fire fighting training devices similar to that described in U.S. Pat. No. 5,055,050, has shown that the accumulation of propane gas in and about the apparatus during the fire fighting training exercise is a common occurrence. The dangers of this situation are compounded by the fact that the injected smell ingredient normally added to the propane to facilitate its detection becomes absorbed by the water so that the presence of extraneous, non-combusted gas is not evident by smell. Furthermore, the stoichiometric or combustible gas concentrations may not be consistently and continuously present, but may evolve over time, subsequent to a burn.
There is also a continuing threat that the unprotected pilot flame will be extinguished by the fire fighting agents being applied to the simulated fire. Hence, for the safety of the individuals using training devices which utilize an over-water combustion system it is critical to ensure the continuing presence of an unquenched pilot flame of significant size, capable of igniting persisting gas traces both during and after the main burn, even when the apparatus is shut down, and the burn terminated.
U.S. Pat. No. 4,983,124 to Ernst et al. discloses an ignition system intended to enhance the stability of a pilot flame during the application of various extinguishing agents to a fire fighting training device similar to the "real" fire training systems described herein. The device disclosed in U.S. Pat. No. 4,983,124 comprises a pilot chamber into which a pilot gas/air mixture is introduced from a burner control enclosure via a pilot nozzle. The mixture is ignited using a rear-mounted spark igniter which provides spark within the nozzle igniting the gas/air mixture before it exits the nozzle. Once ignited, the stability of the flame is enhanced by the introduction of additional air into the pilot chamber. The air surrounds the nozzle and pilot flame, providing available combustion air to the pilot flame if the environmental conditions at the burner require changes in the fuel/air ratio.
The device described in U.S. Pa. No. 4,983,124 is designed to be used with a dry system and is not suited for use in an over-water combustion system. The ignition system and pilot guard assembly disclosed in U.S. Pat. No. 4,983,124 would not sufficiently protect the pilot flame from extinguishing, nor is it suitable for igniting the type of fuel used in an over-water combustion system.
Thus, what is needed in the art is a pilot ignition system which provides for a constant and stable flame under fire fighting training conditions which is of significant size, and is capable of igniting persisting gas traces both during and after the main burn, even when the apparatus is shut down, and the burn terminated.